1. Field of Invention
The present invention relates to a pneumatic ratchet wrench, more particularly to a pneumatic ratchet wrench that has a small volume and can be assembled easily.
2. Description of the Related Art
With reference to FIGS. 3 and 4, a conventional pneumatic ratchet wrench has a body (30), an air input valve (31), a switch (32), a propeller (33), a gear assembly (34), an eccentric spindle (35), a lever (36), a sleeve (37), a nut (38), a washer (402) and a head (40).
The body (30) has a front end, a rear end, a top, a bottom, a through hole (303), a longitudinal through hole (304), an inner surface, a longitudinal cavity (301) and a threaded end (302). The longitudinal cavity (301) is defined in the body (30). The threaded end (302) is defined in the inner surface near the front end. The through hole (303) is defined in the body (30) from the top to the bottom. The longitudinal through hole (304) is defined in the body (30) and communicated with the through hole (303).
The air input valve (31) is mounted inside the rear end of the body (30) and has a rear end, a front end, a joint (311) and an airway (312). The joint (311) is defined at the rear end of the air input valve (31). The airway (312) is longitudinally defined through the air input valve (31) and communicated with the through hole (303) in the body (30).
The switch (32) is mounted in the through hole (303) in the body (30) and has a button, a valve (322) and a spring (323). The button is mounted inside the through hole (303) in the body (30) at the top. The spring (323) has two ends, and one end of the spring (323) abuts the button and the other end of the spring (323) abuts the valve (322). The valve (322) has an extended end extending out the bottom of the body (30).
The propeller (33) is mounted in the longitudinal cavity (301) in the body (30) and communicated with the longitudinal through hole (304) in the body (30). The propeller (33) has multiple vanes (331), a spindle (332) and a gear-like part (333). The spindle (332) has a front end, a middle end and an outer surface. The vanes (331) are respectively mounted on the outer surface of the spindle (332) at the middle end, and the gear-like part (333) is defined on the outer surface of the spindle (332) at the front end.
The gear assembly (34) is mounted on the front end of the propeller (33) and has a cap (341) and three gears (342). The gears (342) are respectively engaged with the gear-like part (333) of the propeller (33). The cap (341) is mounted on the gears (342) and has a gear-like central hole.
The eccentric spindle (35) is mounted on the cap (341) of the gear assembly (34) and has a center, a front end, a rear end, an outer surface, a rod (351) and a gear-like part. The rod (351) is mounted on the front end of the eccentric spindle (35) away from the center. The gear-like part is defined in the outer surface of the eccentric spindle (35) at the rear end and engaged with the gear-like central hole in the cap (341).
The lever (36) is pivotally mounted on the bottom of the body (30) and abuts the extended end of the valve (322).
The sleeve (37) is partially mounted inside the longitudinal cavity (301) in the body (30) and has a teeth-like inner surface and a threaded outer surface. The threaded outer surface of the sleeve (37) is screwed in the threaded end (302) of the body (30) and the teeth-like inner surface of the sleeve (37) is engaged with gear assembly (34). The nut (38) is screwed on the threaded outer surface of the sleeve (37).
The head (40) is mounted on the nut (38) and has a U-shaped bracket (401) g and a ratchet head (41). The U-shaped bracket (401) has a front end, a rear end and two mounting holes. The ratchet head (41) is received inside the U-shaped bracket (401) and has a fan-shaped action part (411) and a post (416). The post (416) has a top, a bottom, a side surface (not numbered), a set of teeth (418), a rod (417) and a lock washer (42). The rod (417) is formed on the bottom of the post (416). The set of teeth (418) is defined in the side surface of the post (416). The lock washer (42) is mounted in the U-shaped bracket (401) on the fan-shaped action part (411). The fan-shaped action part (411) has a front end, a rear end, a central hole, a ratchet inner surface (412), a recess (413) and a connector (414). The ratchet inner surface (412) is mounted inside the central hole of the fan-shaped action part (411) and engaged with the set of teeth (418) in the post (416) allowing one direction movement. The recess (413) is defined in the rear end of the fan-shaped action part (411). The connector (414) is received inside the recess (413) and has a hole (415). The hole (415) is defined in the connector (414) and the rod (351) is mounted through the hole (415) in the connector (414).
When the conventional pneumatic ratchet wrench is used, a tool head is mounted on the rod (417), and the lever (36) is pressed. A provided air passes through the air input valve (31) from the joint (311), and the air passes through the airway (312), the through hole (303) and the longitudinal through hole (304) to drive the vanes (331) on the propeller (33). The gear assembly (34) reduces the speed of the driven propeller (33) and the eccentric spindle (35) will also be driven by the propeller (33). Because the connector (414) is mounted on the eccentric spindle (35) and connected to the ratchet head (411), the ratchet head (411) will swing in the U-shaped bracket (401). The swinging ratchet head (411) drives the post (416) by the set of teeth (418) engaged with the ratchet inner surface (412) of the ratchet head (411) and the tool head mounted on the rod (417) will be driven.
However, the disadvantages of the conventional pneumatic ratchet wrench are described as follow.
1. The volume of the conventional pneumatic ratchet wrench is too large, and so a person cannot use the pneumatic ratchet wrench in a small space easily.
2. The components of the conventional pneumatic ratchet wrench are many and complex, and a person cannot assemble or repair the pneumatic ratchet wrench easily.
The pneumatic ratchet wrench in accordance with the present invention obviates or mitigates the aforementioned problems.